Pauli flow finding algorithm

[d1ssk]

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Context (if applicable):

Description of the change: Add Pauli flow finding method following the algorithm algorithm described in EPTCS 343, 2021, pp. 50-101.

Related issue:

93

also see that checks (github actions) pass. If lint check keeps failing, try installing black==22.8.0 as behavior seems to vary across versions.

[d1ssk]

@masa10-f In the flow/gflow checker, isn't it redundant to examine the properties of the flow and its odd neighbor matrix? This is because dependencies are checked in get_layers_from_flow, and if there are any issues, the result will become False there. Indeed, even if the part that examines that matrix is commented out, the tests still pass.

[masa10-f]

@d1ssk You're right. I didn't give it much thought. Could you delete matrix check in this PR?

[masa10-f]

@d1ssk If the computational complexity is mentioned in the original paper, can you check the performance of our Pauli flow finding method is consistent with it?

[masa10-f]

@d1ssk Thanks for your commitment! You can merge this branch now.